Formation of Chiral Quaternary Carbon Stereocenters Using Silylene Transfer Reactions: Enantioselective Synthesis of (+)-5-<i>epi</i>-Acetomycin
作者:Stacie A. Calad、K. A. Woerpel
DOI:10.1021/ol063072p
日期:2007.3.1
Chiral quaternarycarbonstereocenters can be established with high diastereoselectivity by a silylene transfer/Ireland-Claisen rearrangement. The utility of this method was demonstrated by application to a synthesis of (+)-5-epi-acetomycin. [reaction: see text]
Allyl-aryl coupling between allylic acetates and arylboronicacids took place in the presence of catalytic amounts of Pd(OAc)(2), 1,10-phenanthroline, and AgSbF(6) with high gamma-selectivity and E/Z-selectivity. The reaction of an optically active allylic acetates with an alpha-stereogenic center proceeded with excellent alpha-to-gamma chirality transfer with syn-selectivity and gave the corresponding
Stereoselective Reactions of Acyclic Allylic Phosphates with Organocopper Reagents
作者:Jennifer L. Belelie、J. Michael Chong
DOI:10.1021/jo0104431
日期:2001.8.1
the size of R(2) affected both the regioselectivity and stereoselectivity of the displacement. Larger R(2) groups gave higher regio- and stereoselectivities: with R(2) = 3-pentyl, >98% S(N)2' regioselectivity and >98% anti stereoselectivity were observed. Bn(2)CuCNLi(2) gave stereoselectivities comparable to those observed with n-Bu(2)CuCNLi(2) but t-Bu(2)CuCNLi(2) exhibited much lower diastereofacial
Highly Diastereoselective and Enantiospecific Allylation of Ketones and Imines Using Borinic Esters: Contiguous Quaternary Stereogenic Centers
作者:Jack L.-Y. Chen、Varinder K. Aggarwal
DOI:10.1002/anie.201407127
日期:2014.10.6
allylic boronic esters are not sufficiently reactive to react with ketones and imines. However, they can be converted into the corresponding borinicesters by the sequential addition of nBuLi and TFAA. These reactive intermediates possess the perfect balance between reactivity and configurational stability. Their enhanced reactivity allows the highly selective allylation of both ketones and ketimines